Expanded glass aggregates from mining and food industry waste

Abstract

The use of aggregates in the construction industry reaches the manufacture of concretes and mortars, prefabricated products, agglomerated asphalts, ballast for railroads, breakwaters, etc. Although dense aggregates have been traditionally used, during the last decades there have been an increasing demand for lightweight aggregates. The production of lightweight aggregates involves a high consumption of natural resources and energy, due to the high temperature required for the manufacture. Moreover, if this energy is obtained from fossil fuels, the associated environmental cost is also very high. The objective of this study is to prepare bloated glass from different waste such as cullet (base material) and carbonated wastes. The carbonated waste from mining (magnesite production) and food industry (eggshells and mussel shells) were used as bloating agents.

The mixtures of the different waste were subjected to firing at temperature between 700-1100ºC in a muffle furnace. Moreover, in order to study the use of a renewable energy, additional tests were performed using a solar energy simulator for comparison.

The effect of the different processing parameters (particle size of cullet, percentage and nature of foamy agents, firing rate, firing temperature and time) on the characteristics of the expanded glasses were studied. Lightweight aggregates with values of density ranged between 0.55-0.80 g·cm-3, and compressive strength between 0.65-1.10 MPa were obtained. The results using the solar simulator indicated that solar energy can be used as an alternative a less contaminant energy source.